VB 的 CTYPE() 的正确 C# 转换对应项
下面是我将其移植到 C# 重写中的 VB 片段。我的问题是作业后的 receipt_date 是多少？它仍然是一个对象还是一个字符串？
Dim receipt_date As Object
receipt_date = CType(dr.Item("RECTDT"), String)
这是正确的 C# 对应项吗？
object receipt_date;
receipt_date = dr["RECTDT"].ToString();
这两个执行后，VB 版本的 receipt_date 是否等于 C# 版本？如果不是，我需要做什么才能做到这一点？谢谢
The below is a snippet from VB that I am porting to a C# rewrite. My question is what is receipt_date after the assignment? Is it still an object or is it a string?
Dim receipt_date As Object
receipt_date = CType(dr.Item("RECTDT"), String)
Would this be the correct C# counterpart?
object receipt_date;
receipt_date = dr["RECTDT"].ToString();
After both of these execute would the VB version, receipt_date be equal to the C# version? If not, what do I need to do to make it so? Thanks
如果你对这篇内容有疑问，欢迎到本站社区发帖提问 参与讨论，获取更多帮助，或者扫码二维码加入 Web 技术交流群。
绑定邮箱获取回复消息
由于您还没有绑定你的真实邮箱，如果其他用户或者作者回复了您的评论，将不能在第一时间通知您！
发布评论
评论（2）
是的，您最终会得到相同的结果。它在语义上与 VB 版本不同（您显式调用
ToString()而不是使用CType，这大致相当于 C# 中的强制转换），但功能相同。它也更安全，因为在数据库中转换 null 值（在运行时为DBNull）会引发异常。不过，为了全面起见，实际的 C# 对应内容是这样的：
不过，作为风格的一点，尽量避免隐式类型（即使用
var关键字而不是说string或int）用于简单类型。当类型将来可能发生变化（并且并不重要），或者类型很长和/或复杂并且var使其更具可读性时，var非常有用。在这种情况下，我建议：Yes, you would end up with the same result. It's semantically different from the VB version (you're calling
ToString()explicitly instead of usingCType, which is loosely equivalent to a cast in C#), but it's functionally identical. It's also safer, since casting a null value in the database (which would beDBNullin the runtime) would throw an exception.Just for the sake of being comprehensive, though, the actual C# counterpart would be this:
As a point of style, though, try to avoid implicit typing (i.e., using the
varkeyword instead of sayingstringorint) for simple types.varis useful when the type might change in the future (and isn't important), or if the type is long and/or complex andvarmakes it more readable. In this instance, I would suggest:VB 的
CType关键字或多或少相当于Convert.ToString，尽管不完全相同。因此，VB 中的以下内容...
...最好（或最接近）翻译为 C# 中的以下内容。
顺便说一下，
CType(..., String)被编译为Microsoft.VisualBasic.CompilerServices.Conversions.ToString。VB's
CTypekeyword is more or less equivalent toConvert.ToStringthough not exactly the same.So the following in VB...
...would be best (or most closely) translated to the following in C#.
By the way
CType(..., String)gets compiled intoMicrosoft.VisualBasic.CompilerServices.Conversions.ToString.